If this box has a red border, this page's own CSS is working.
A paragraph of body text. Look at the font, the size, and the width of this line. Browser default is Times New Roman at 16px, running the full width of the window. If you're seeing a sans-serif face, or the text is capped at some comfortable reading width, something else is styling this page.
A second paragraph, to check the spacing between them. Here is a link, bold text, and italic text.
A blockquote. Themes love to restyle these, so it's a useful tell.
| Column A | Column B |
|---|---|
| Cell one | Cell two |
Default table borders are invisible. If you see borders, stripes, or padding on the table above, a stylesheet is reaching it.
End of test page.